SCS Storms

[SMIAH]

Is it suitable for a peak flow estimation to use a 6-hr storm duration with a SCS type II repartition?

Procedure:

- Calculating total rainfall depth related to a local IDF curve for a duration of 6 hour (for a specific probability e.g. 1/25 years).

- Then using SMADA 6.0, clicking on SCS type II for the rainfall distribution

Should the 24-hour duration be used...

I know there's alot of post related to this subject - just want to have a quick answer

 

[psmart]

A 24-hour Type II distribution should only be used at the intended 24-hour duration. Not sure exactly how SMADA handles this, but compressing a 24-hour storm to 6-hours will increase the peak intensity 4-fold. What you really want is the middle 6-hours of the 24-hour storm. The best solution is to use a specific 6-hour distribution.


Peter Smart
HydroCAD Software

http://www.hydrocad.net

 

[SMIAH]

Indeed SMADA 6.0 don't put any warning about this.

Thanks.